1. Field of the Art
This invention relates to a reference electrode to be a reference for calculating or measuring an electrode potential, a salt bridge to joint two kinds of electrolyte solutions in an electrochemical measurement cell or a chemical cell and an ionic concentration measuring device to measure an ionic concentration in a sample solution by the use of the reference electrode and the salt bridge.
2. Explanation of the Related Art
A most widely used method for measuring pH is a method using a glass electrode wherein a reactive membrane is a glass membrane, and a surface of the glass membrane generates an electric potential (difference of a potential) in accordance with pH of a sample solution when the glass electrode contacts the sample solution. In order to measure the difference of the potential, an electric potential as being a reference is required, which requires a reference electrode that can present a certain reference potential in addition to the glass electrode.
However, if a liquid junction potential generated at a time when the internal solution of the reference electrode contacts the sample solution varies, a reference potential presented by the reference electrode also varies. Then a reference electrode with an arrangement that an electrode made of Ag/AgCl or Hg/Hg2Cl2 is immersed in an internal solution comprising a KCl solution of high concentration (3.3 mol/L˜saturation) and an internal solution contacts a sample solution through a liquid junction comprising a porous material such as ceramics or glass has been used commonly in order to keep the variations of a liquid junction potential between the internal solution and the sample solution to a minimum. (Japan Patent Laid open number 11-258197)